I would just open the bolt, run a cleaning patch or two through it for basic cleaning.

I don't know if you have tried to take it down but I am pretty sure that if you open the lever and unscrew the screw holding it in place it will come out and after that you can remove the bolt by pulling it out of where it sits.

With the bolt out you can more easily clean the bolt and it lets you get at more of the insides with a q-tip for a more thorough cleaning.

Unless the gun starts to malfunction or something of that nature I wouldn't take it down further very often. Maybe just every few months to yearly depending on how much it got shot. Maybe just once to get a sense of how it works, I appreciated the action of the Marlin 336 when I took it apart but it is a whole lot less pieces than 30.